Umemoto, Teruo published the artcilePower- and structure-variable fluorinating agents. The N-fluoropyridinium salt system, Computed Properties of 107263-95-6, the publication is Journal of the American Chemical Society (1990), 112(23), 8563-75, database is CAplus.
The usefulness of the N-fluoropyridinium salt system as a source of fluorinating agents was examined by using substituted or unsubstituted N-fluoropyridinium triflates, N-fluoropyridinium salts possessing other counteranions, and two N-fluoropyridinium-2-sulfonates (I). Electrophilic fluorinating power varied remarkably according to the electronic nature of the ring substituents. This power increased as the electron d. of pos. N sites decreased, and this was correlated to the pKa values of the corresponding pyridines. By virtue of this variation, it was possible to fluorinate a wide range of nucleophile substrates differing in reactivity, e.g., aromatics, carbanions, active methylene compounds, enol alkyl or silyl ethers, vinyl acetates, ketene silyl acetals, and olefins. All the reactions could be explained on the basis of a one-electron-transfer mechanism. N-Fluoropyridinium salts showed high chemoselectivity in fluorination, the extent depending on the reactive moiety. Selective 9α-fluorination of steroids was carried out with the tris(trimethylsilyl ether) of a triketo steroid. Regio- or stereoselectivity in fluorination was determined by N-fluoropyridinium salt structure. Steric bulkiness of the N-F surroundings hindered the orthofluorination of phenols and aniline derivatives, while the capacity for H bonding on the part of the counteranions prompted this process, and I underwent this fluorination exclusively or almost so. Two bulky N-fluoropyridinium triflates preferentially attacked the 6-position of the conjugated vinyl ester of a steroid from the unhindered β-direction to give a thermally unstable 6β-fluoro isomer. N-Fluoropyridinium salt systems can serve as a source of the most ideal fluorinating agents for conducting desired selective fluorination through fluorinating capacity or structural alteration.
Journal of the American Chemical Society published new progress about 107263-95-6. 107263-95-6 belongs to pyridine-derivatives, auxiliary class Fluorination reagent, name is 1-Fluoropyridiniumtriflate, and the molecular formula is C18H35NO, Computed Properties of 107263-95-6.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem